Abnormalities of lipid absorption and metabolism are associated with risk for cardiovascular diseases. Thus, there is a need to fully characterize the factors that influence these processes. We have demonstrated that orosensory exposure to dietary fat augments the postprandial rise of serum triacylglycerol (TAG) in humans, in part, through modification of absorptive processes. Because dietary manipulations are the preferred approach for prevention and management of lipid disorders, a better understanding of an orosensory contribution is especially important. This knowledge may hold additional public health, clinical and commercial implications as well. Oral sensory exposure may modulate process associated with taste perception generally and responses modulating energy and essential fatty acid balances. The Specific Aims are to: 1. Clarify the mechanisms of fat perception; 2. Establish the practical relevance of oral fat exposure effects and 3. Elucidate basic issues in lipid metabolism and the health significance of oral fat exposure. Aim 1 will be addressed through four psychophysical studies. One will document the taste component for dietary fat and three others will explore possible mechanisms including fatty acid transport across taste receptor cell membranes, modulation of receptor cell responsiveness to other taste compounds and taste cell activation by a fatty acid oxidation product. Three additional studies will characterize the TAG response to oral fat exposures under more realistic feeding conditions to establish is practical implications (Aim 2). One will explore the TAG response to taste mixtures commonly encountered in food. Others will determine the minimal stimulation time and gastric lipid load required to elicit the TAG response as will as the importance of stimulation timing relative to lipid loading on the magnitude of the TAG response. Finally, our most recent observation of a very early TAG peak that contains lipid from a previous meal and is responsive to oral fat exposure, has raised interest in an oral fat exposure effect on lipid absorption processes and the health significance of the effect. This will be explored through stable isotope tracer studies for Aim 3. The proposed work will hold important public health, clinical, commercial and basic biological implications. [unreadable] [unreadable]